Android Open Source - TaskButler Task Date Due Comparator

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License

The source code is released under:

GNU General Public License

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Java Source Code

/*
 * TaskDateDueComparator.java// w  w w  .j a v  a2  s . c o  m
 * 
 * Copyright 2012 Jonathan Hasenzahl, James Celona, Dhimitraq Jorgji
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package edu.worcester.cs499summer2012.comparator;

import java.util.Comparator;

import edu.worcester.cs499summer2012.task.Task;

/**
 * Comparator for sorting tasks by due date.
 * @author Jonathan Hasenzahl
 */
public class TaskDateDueComparator implements Comparator<Task> {
  
  /**
   * Compares two tasks by their due dates. Tasks with no due date are ordered
   * after those with a due date.
   * @param lhs the first task
   * @param rhs the second task
   * @return A negative value if the first task is due first, a positive
   *         value if the second task is due first, or 0 if they are due at
   *         the same time
   */  
  public int compare(Task lhs, Task rhs) {
    if (!lhs.hasDateDue()) {
      // Case 1: lhs has no due date
      if (rhs.hasDateDue()) {
        // Case 1a: rhs has a due date and is ordered first
        return 1;
      } else {
        // Case 2a: rhs has no due date and they are equal
        return 0;
      }
    }
    else {
      // Case 2: lhs has a due date
      if (!rhs.hasDateDue()) {
        // Case 2a: rhs has no due date and is ordered second
        return -1;
      }
      else {
        // Case 2b: rhs has a due date
        // Ex. LHS -> date 5000ms (earlier)
        //     RHS -> date 6000ms (later)
        //     LHS - RHS = 5000 - 6000 = -1000 = LHS ordered first
        long diff = lhs.getDateDue() - rhs.getDateDue();
        
        if (diff < 0)
          return -1;
        
        if (diff > 0)
          return 1;
        
        return 0;
      }
    }
  }
}

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